# BeLLM: Backward Dependency Enhanced Large Language Model for Sentence Embeddings

arXiv: https://arxiv.org/abs/2311.05296 · HTML: https://mlsanity.com/paper/2311.05296/

## Key facts

- Cited by 32 papers in the map (data through 14 Oct 2026).
- Builds on 26 of its 61 references that are in the map.
- First posted on arXiv 9 Nov 2023.

## Builds on (most cited first, 26 of 26)

- [Attention Is All You Need](https://mlsanity.com/paper/1706.03762/) (2017)
- [BERT: Pre-training of Deep Bidirectional Transformers for Language Understanding](https://mlsanity.com/paper/1810.04805/) (2018)
- [LoRA: Low-Rank Adaptation of Large Language Models](https://mlsanity.com/paper/2106.09685/) (2021)
- [Llama 2: Open Foundation and Fine-Tuned Chat Models](https://mlsanity.com/paper/2307.09288/) (2023)
- [Sentence-BERT: Sentence Embeddings using Siamese BERT-Networks](https://mlsanity.com/paper/1908.10084/) (2019)
- [Scaling Laws for Neural Language Models](https://mlsanity.com/paper/2001.08361/) (2020)
- [Distributed Representations of Words and Phrases and their Compositionality](https://mlsanity.com/paper/1310.4546/) (2013)
- [QLoRA: Efficient Finetuning of Quantized LLMs](https://mlsanity.com/paper/2305.14314/) (2023)
- [Scaling Instruction-Finetuned Language Models](https://mlsanity.com/paper/2210.11416/) (2022)
- [A Broad-Coverage Challenge Corpus for Sentence Understanding through Inference](https://mlsanity.com/paper/1704.05426/) (2017)
- [Billion-scale similarity search with GPUs](https://mlsanity.com/paper/1702.08734/) (2017)
- [Deep contextualized word representations](https://mlsanity.com/paper/1802.05365/) (2018)
- [SimCSE: Simple Contrastive Learning of Sentence Embeddings](https://mlsanity.com/paper/2104.08821/) (2021)
- [A large annotated corpus for learning natural language inference](https://mlsanity.com/paper/1508.05326/) (2015)
- [Understanding Contrastive Representation Learning through Alignment and Uniformity on the Hypersphere](https://mlsanity.com/paper/2005.10242/) (2020)
- [SemEval-2017 Task 1: Semantic Textual Similarity - Multilingual and Cross-lingual Focused Evaluation](https://mlsanity.com/paper/1708.00055/) (2017)
- [Super-NaturalInstructions: Generalization via Declarative Instructions on 1600+ NLP Tasks](https://mlsanity.com/paper/2204.07705/) (2022)
- [How Contextual are Contextualized Word Representations? Comparing the Geometry of BERT, ELMo, and GPT-2 Embeddings](https://mlsanity.com/paper/1909.00512/) (2019)
- [Supervised Learning of Universal Sentence Representations from Natural Language Inference Data](https://mlsanity.com/paper/1705.02364/) (2017)
- [SentEval: An Evaluation Toolkit for Universal Sentence Representations](https://mlsanity.com/paper/1803.05449/) (2018)
- [ConSERT: A Contrastive Framework for Self-Supervised Sentence Representation Transfer](https://mlsanity.com/paper/2105.11741/) (2021)
- [Whitening Sentence Representations for Better Semantics and Faster Retrieval](https://mlsanity.com/paper/2103.15316/) (2021)
- [DiffCSE: Difference-based Contrastive Learning for Sentence Embeddings](https://mlsanity.com/paper/2204.10298/) (2022)
- [An Unsupervised Sentence Embedding Method by Mutual Information Maximization](https://mlsanity.com/paper/2009.12061/) (2020)
- [Whitening-based Contrastive Learning of Sentence Embeddings](https://mlsanity.com/paper/2305.17746/) (2023)
- [HiCL: Hierarchical Contrastive Learning of Unsupervised Sentence Embeddings](https://mlsanity.com/paper/2310.09720/) (2023)

## Built on by (most cited first, 30 of 32)

- [LLM2Vec: Large Language Models Are Secretly Powerful Text Encoders](https://mlsanity.com/paper/2404.05961/) (2024)
- [Generative Representational Instruction Tuning](https://mlsanity.com/paper/2402.09906/) (2024)
- [Token Prepending: A Training-Free Approach for Eliciting Better Sentence Embeddings from LLMs](https://mlsanity.com/paper/2412.11556/) (2024)
- [Meta-Task Prompting Elicits Embeddings from Large Language Models](https://mlsanity.com/paper/2402.18458/) (2024)
- [GenEOL: Harnessing the Generative Power of LLMs for Training-Free Sentence Embeddings](https://mlsanity.com/paper/2410.14635/) (2024)
- [Contrastive Prompting Enhances Sentence Embeddings in LLMs through Inference-Time Steering](https://mlsanity.com/paper/2505.12831/) (2025)
- [ProRank: Prompt Warmup via Reinforcement Learning for Small Language Models Reranking](https://mlsanity.com/paper/2506.03487/) (2025)
- [Read Before You Think: Mitigating LLM Comprehension Failures with Step-by-Step Reading](https://mlsanity.com/paper/2504.09402/) (2025)
- [Position: Text Embeddings Should Capture Implicit Semantics, Not Just Surface Meaning](https://mlsanity.com/paper/2506.08354/) (2025)
- [Large Language Models Are Overparameterized Text Encoders](https://mlsanity.com/paper/2410.14578/) (2024)
- [From Word Vectors to Multimodal Embeddings: Techniques, Applications, and Future Directions For Large Language Models](https://mlsanity.com/paper/2411.05036/) (2024)
- [MAGNET: Augmenting Generative Decoders with Representation Learning and Infilling Capabilities](https://mlsanity.com/paper/2501.08648/) (2025)
- [New Encoders for German Trained from Scratch: Comparing ModernGBERT with Converted LLM2Vec Models](https://mlsanity.com/paper/2505.13136/) (2025)
- [Enhancing Unsupervised Sentence Embeddings via Knowledge-Driven Data Augmentation and Gaussian-Decayed Contrastive Learning](https://mlsanity.com/paper/2409.12887/) (2024)
- [RegionMarker: A Region-Triggered Semantic Watermarking Framework for Embedding-as-a-Service Copyright Protection](https://mlsanity.com/paper/2511.13329/) (2025)
- [Hierarchical Token Prepending: Enhancing Information Flow in Decoder-based LLM Embeddings](https://mlsanity.com/paper/2511.14868/) (2025)
- [Generative Deduplication For Socia Media Data Selection](https://mlsanity.com/paper/2401.05883/) (2024)
- [ExLM: Rethinking the Impact of [MASK] Tokens in Masked Language Models](https://mlsanity.com/paper/2501.13397/) (2025)
- [Educational Cone Model in Embedding Vector Spaces](https://mlsanity.com/paper/2512.04227/) (2025)
- [Analyzing Diffusion and Autoregressive Vision Language Models in Multimodal Embedding Space](https://mlsanity.com/paper/2602.06056/) (2026)
- [Privately Learning from Graphs with Applications in Fine-tuning Large Language Models](https://mlsanity.com/paper/2410.08299/) (2024)
- [CASE -- Condition-Aware Sentence Embeddings for Conditional Semantic Textual Similarity Measurement](https://mlsanity.com/paper/2503.17279/) (2025)
- [PoLi-RL: A Point-to-List Reinforcement Learning Framework for Conditional Semantic Textual Similarity](https://mlsanity.com/paper/2510.04080/) (2025)
- [Focusing Condition: Inference-Time Self-Contrastive Steering Elicits Better Conditional Text Embeddings in LLMs](https://mlsanity.com/paper/2609.32684/) (2026)
- [Causal2Vec: Improving Decoder-only LLMs as Embedding Models through a Contextual Token](https://mlsanity.com/paper/2507.23386/) (2025)
- [Causal Attention with Lookahead Keys](https://mlsanity.com/paper/2509.07301/) (2025)
- [Text2Token: Unsupervised Text Representation Learning with Token Target Prediction](https://mlsanity.com/paper/2510.10224/) (2025)
- [Geometry-Aware Localized Watermarking for Copyright Protection in Embedding-as-a-Service](https://mlsanity.com/paper/2604.11344/) (2026)
- [Modular Representation Compression: Adapting LLMs for Efficient and Effective Recommendations](https://mlsanity.com/paper/2604.18146/) (2026)
- [Embedding-based In-Context Prompt Training for Enhancing LLMs as Text Encoders](https://mlsanity.com/paper/2605.01372/) (2026)

## Abstract (arXiv)

Sentence embeddings are crucial in measuring semantic similarity. Most recent studies employed large language models (LLMs) to learn sentence embeddings. Existing LLMs mainly adopted autoregressive architecture without explicit backward dependency modeling. Therefore, we examined the effects of backward dependencies in LLMs for semantic similarity measurements. Concretely, we propose a novel model: backward dependency enhanced large language model (BeLLM). It learns sentence embeddings via transforming specific attention layers from uni- to bi-directional. We extensively experiment across various semantic textual similarity (STS) tasks and downstream applications. BeLLM achieves state-of-the-art performance in varying scenarios. It shows that auto-regressive LLMs benefit from backward dependencies for sentence embeddings.